1. Field of the Invention
The present invention relates to a liquid ejection head.
2. Description of the Related Art
A typical liquid ejection head is disclosed in Japanese Patent Laid-Open No. 2002-019120. FIGS. 11A, 11B, and 11C are schematic configuration diagrams of the typical liquid ejection head disclosed in Japanese Patent Laid-Open No. 2002-019120. FIG. 11A is a perspective view, FIG. 11B is an enlarged sectional view taken along line XIB-XIB of FIG. 11A, and FIG. 11C is an enlarged sectional view taken along line XIC-XIC of FIG. 11A.
The liquid ejection head 100 can be mounted in a recording apparatus main body (not shown) that performs recording on a recording medium such as paper. As shown in FIG. 11A, the liquid ejection head 100 includes two rectangular recording element substrates 1a and 1b and a supporting substrate 8 that supports the recording element substrates 1a and 1b. 
The liquid ejection head 100 includes an electric contact substrate 16 and an electric wiring substrate 11 for transmitting electric pulse signals from the recording apparatus main body to the recording element substrates 1a and 1b when the liquid ejection head 100 is mounted in the recording apparatus main body. The electric wiring substrate 11 is supported by the supporting substrate 8.
As shown in FIG. 11B and FIG. 11C, the recording element substrate 1a includes a substrate 2 and an ejection port plate 5 formed so as to cover the substrate 2. Ejection energy generating elements 4 that are electrothermal transducers are provided on the substrate 2. Ejection ports 6 are formed in the ejection port plate 5 so as to face the ejection energy generating elements 4.
A recess 17 is formed between the four sides of the recording element substrate 1a and a supporting plate 9. A groove 28 narrower than the recess 17 is formed in part of the supporting substrate 8 corresponding to the recess 17. Thus, the recording element substrate 1a is completely surrounded by the recess 17 and the groove 28.
As shown in FIG. 11C, electrode terminals 13 that electrically connect the recording element substrate 1a and the electric wiring substrate 11 are disposed over the recess 17. In response to an electric pulse signal transmitted from the electric wiring substrate 11, the recording element substrate 1a drives the ejection energy generating elements 4 and ejects ink from the ejection ports 6.
When the liquid ejection head 100 is manufactured, first sealing resin 18 is injected in an uncured state into the recess 17 by a dispense method. The uncured first sealing resin 18 injected into the recess 17 flows owing to capillary action along the groove 28 and fills the recess 17. The first sealing resin 18 filling the recess 17 is cured by being heated.
In the liquid ejection head 100, the corrosion of the supporting substrate 8 by ink and a short circuit between the recording element substrate 1a and the electric wiring substrate 11 due to ink can be prevented by the first sealing resin 18.
In addition, as shown in FIG. 11C, layers of second sealing resin 19 are formed so as to cover the electrode terminals 13. When the liquid ejection head 100 is manufactured, the second sealing resin 19 is applied in an uncured state to the electrode terminals 13 and is then cured by being heated as with the first sealing resin 18.
In the liquid ejection head 100, the electrode terminals 13 can be protected by the second sealing resin 19, and the corrosion or the like of the electrode terminals 13 by ink can be prevented.
When the liquid ejection head 100 shown in FIGS. 11A to 11C is manufactured, as described above, uncured first sealing resin 18 is injected into the recess 17 over the groove 28. At that time, since the groove 28 is narrow, owing to the surface tension or the like of the uncured first sealing resin 18, sometimes the uncured first sealing resin 18 does not enter some parts of the groove 28 from the recess 17.
In such a case, after the recess 17 is filled with the uncured first sealing resin 18, air remains in the uncured first sealing resin 18. The air in the uncured first sealing resin 18 forms bubbles, and sometimes the bubbles grow up to 1 mm or more in diameter.
If the bubbles burst in the uncured first sealing resin 18, the uncured first sealing resin 18 may be scattered about and may adhere to the recording element substrate 1a and the like. This may prevent the recording element substrate 1a from appropriately ejecting ink.
When the first sealing resin 18 and the second sealing resin 19 are heated to cure them, sometimes the bubbles in the first sealing resin 18 move into the second sealing resin 19. In this case, a gap may be formed between the electrode terminals 13 and the second sealing resin 19 covering them and may cause defective sealing of the electrode terminals 13. The liquid ejection head described in Japanese Patent Laid-Open No. 2002-019120 has such problems.